In the middle of the Cold War, Naked Snake, the man who would later be known as Big Boss, infiltrates the Soviet Union to escort a defecting scientist, Sokolov. However, the mission ends in failure when Snake's mentor—The Boss, a soldier known as the mother of special forces—betrays him, and Sokolov is captured by Colonel Volgin of the GRU. One week later, Snake returns to Soviet territory to rescue Sokolov and eliminate The Boss.
